The other open option though, is the stretch-backports package, you mentioned. I think, I try this first.

Hi! I have mainboard ASRock N68-GS4 with the built-in NVIDIA GeForce 7025 / nForce 630a GPU. Stretch-backports obviously does not work. nouveau is working well with the simple graphics, but hangs my host when playing videos using vlc.

The system is upgraded to Buster, so downgrade is not possible in easy way (well it would be better if some warning would be issued before the upgrade). The simplest for me would be to quickly buy working graphic card. I do not need anything special, but something working with the existing free software in Debian: 3d games, video players (vlc, mpv) etc. Can somebody recommend something working for me?